Adsorption of gold on albite in acidic chloride media

Abstract

The ability of albite, an aluminosilicate mineral typical of those present in many gold ores, to adsorb gold is examined at varied pH levels in chloride media. The adsorption of gold on albite is intimately associated with the leaching behaviour of albite in acidic solutions. The preferential leaching of Na and Al from albite leads to the formation of an altered silica-rich surface layer as the gold sorbent. Gold adsorption increases at lower pH due to a greater extent of albite leaching. The majority of gold adsorption onto albite occurs within the first 0.5h of contact, and the gold concentration in solution then increases after an extended contact period due to the partial relocation of the adsorbed gold from the altered albite surface to freshly formed nanoscale silica particles in solution. Surface activation by fine milling increases the extent of gold adsorption on albite, correlated with enhanced leaching of albite. The gold adsorbed on processed albite surface exists as Au3+, Au+ and Au0, indicating the reduction of Au3+ in chloroauric acid to lower oxidation states in the silica-rich layers during adsorption.